Wireless communication systems are widely deployed to provide various types of communication such as voice and data. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), or some other multiple access techniques. A CDMA system provides certain advantages over other types of systems, including increased system capacity.
A CDMA system may be designed to support one or more CDMA standards such as (1) the “TIA/EIA-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), (2) the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), (3) the standard offered by a consortium named “3rd Generation Partnership Project 2” (3GPP2) and embodied in “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems” (the IS-2000 standard), and (4) some other standards. An example non-CDMA system is the GSM system.
A wireless packet data communication system may comprise one or more Packet Data Serving Nodes (PDSNs), each of which connect to one or more Packet Coordination Functions (PCFs), which communicate with one or more mobile stations over a physical channel. To maintain the location of a mobile station within a network and to facilitate network initiated data for transmission to that mobile station, current systems may require a mobile station to register with each PCF as it enters the PCF's coverage area. As a mobile station travels between a group of PCFs, repeated registrations may occur. This registration overhead uses system resources and reduces overall system capacity.
When a mobile station moves from one PCF to another, it is possible for data directed from a PDSN to a mobile station to be lost while the mobile station reregisters with the new PCF. This data loss may result in retransmission, which results in transmission delay and uses system resources and reduces overall system capacity. There is therefore a need in the art for avoiding data loss and reducing registration overhead in a wireless packet data communication system.